Nanofiltration of colored surface water: Quebec's experience

2003 ◽  
Vol 3 (5-6) ◽  
pp. 15-22
Author(s):  
P. Kouadio ◽  
M. Tétrault

Three colored surface water nanofiltration pilot-scale projects were conducted in the province of Quebec (eastern Canada), between November 2000 and March 2002, by the company H2O Innovation (2000) inc., for the municipalities of Lac Bouchette, Latulipe-et-Gaboury and Charlesbourg (now part of Quebec City). Results indicated that nanofiltration permeate quality has an advance on present drinking water regulation standard in Quebec, but important membrane fouling occurred. Fouling can be controlled by pretreatment and optimization of the operating conditions.

2011 ◽  
Vol 11 (1) ◽  
pp. 23-29 ◽  
Author(s):  
P. M. Huck ◽  
S. Peldszus ◽  
C. Hallé ◽  
H. Ruiz ◽  
X. Jin ◽  
...  

Fouling remains one of the major constraints on the use of low pressure membranes in drinking water treatment. Work over the last few years has shown the importance of biopolymers (carbohydrates and protein-like material) as foulants for ultrafiltration (UF) membranes. The purpose of this study was to investigate at pilot scale the use of rapid biofiltration (without prior coagulation or ozone addition) as an innovative pretreatment to reduce fouling of UF membranes. The investigation was carried out on a water with a higher than average DOC and significant temperature variation. The biofilters, each operated at a hydraulic loading of 5 m/h, had empty bed contact times of 5, 10 and 15 minutes. The membrane unit was operated at a flux equivalent to 60 LMH at 20°C. The investigation confirmed the encouraging results obtained in an earlier smaller scale study with essentially the same water. Increased biofiltration contact time (i.e. increased bed depth) led to lower rates of hydraulically irreversible fouling. The initial biofiltration backwash procedure, involving air scour as is common in chemically assisted filtration, led in some cases to an increased rate of membrane fouling immediately after the backwash. An alternative backwashing strategy was developed, however the feasibility of operating with this approach over very long periods of time needs to be confirmed. To assist in full-scale implementation of this “green” and simple pretreatment, the design and operating conditions for the biofilters should be optimized for various types of waters. It is expected that biofiltration pretreatment will be of particular interest for small and/or isolated systems where a higher initial capital cost may be acceptable because of operational simplicity and reduced chemical requirements.


2018 ◽  
Vol 19 (3) ◽  
pp. 855-863 ◽  
Author(s):  
T. Miyoshi ◽  
Y. Takahashi ◽  
T. Suzuki ◽  
R. Nitisoravut ◽  
C. Polprasert

Abstract This study investigated the performance of a hybrid membrane filtration system to produce industrial water from highly-colored surface water. The system consists of a membrane filtration process with appropriate pretreatments, including coagulation, pre-chlorination, and anion exchange (IE) process. The results of the pilot-scale experiments revealed that the hybrid system can produce treated water with color of around 5 Pt-Co, dissolved manganese concentration of no more than 0.05 mg/L, and a silt density index (SDI) of no more than 5 when sufficient coagulant and sodium hypochlorite were dosed. Although the IE process effectively reduced the color of the water, a moderate increase in the color of the IE effluent was observed when there was a significant increase in the color of the raw water. This resulted in a severe membrane fouling, which was likely to be attributed to the excess production of inorganic sludge associated with the increased coagulant dosage required to achieve sufficient reduction of color. Such severe membrane fouling can be controlled by optimising the backwashing and relaxation frequencies during the membrane filtration. These results indicate that the hybrid system proposed is a suitable technology for treating highly-colored surface water.


2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Hanaa M. Ali ◽  
Hanaa Gadallah ◽  
Sahar S. Ali ◽  
Rania Sabry ◽  
A. G. Gadallah

This paper was focused on the investigation of a forward osmosis- (FO-) reverse osmosis (RO) hybrid process to cotreat seawater and impaired water from steel industry. By using this hybrid process, seawater can be diluted before desalination, hence reducing the energy cost of desalination, and simultaneously contaminants present in the impaired water are prevented from migrating into the product water through the FO and RO membranes. The main objective of this work was to investigate on pilot-scale system the performance of the combined FO pretreatment and RO desalination hybrid system and specifically its effects on membrane fouling and overall solute rejection. Firstly, optimization of the pilot-scale FO process to obtain the most suitable and stable operating conditions for practical application was investigated. Secondly, pilot-scale RO process performance as a posttreatment to FO process was evaluated in terms of water flux and rejection. The results indicated that the salinity of seawater reduced from 35000 to 13000 mg/L after 3 hrs using FO system, while after 6 hrs it approached 10000 mg/L. Finally, FO/RO system was tested on continuous operation for 15 hrs and it was demonstrated that no pollutant was detected neither in draw solution nor in RO permeate after the end of operating time.


Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 91
Author(s):  
Margarida Campinas ◽  
Rui M. C. Viegas ◽  
Rosário Coelho ◽  
Helena Lucas ◽  
Maria João Rosa

Pressurized powdered activated carbon/coagulation/ceramic microfiltration (PAC/Alum/MF) was investigated at pilot scale for treating low turbidity and low natural organic matter (NOM) surface waters spiked with organic microcontaminants. A total of 11 trials with clarified or non-clarified waters spiked with pesticides, pharmaceutical compounds, or microcystins were conducted to assess the removal of microcontaminants, NOM (as 254 nm absorbance, A254, and dissolved organic carbon, DOC), trihalomethane formation potential (THMFP), aerobic endospores as protozoan (oo)cysts indicators, bacteriophages as viruses indicators, and regular drinking water quality parameters. PAC/(Alum)/MF achieved 75% to complete removal of total microcontaminants with 4–18 mg/L of a mesoporous PAC and 2 h contact time, with a reliable particle separation (turbidity < 0.03 NTU) and low aluminium residuals. Microcontaminants showed different amenabilities to PAC adsorption, depending on their charge, hydrophobicity (Log Kow), polar surface area and aromatic rings count. Compounds less amenable to adsorption showed higher vulnerability to NOM competition (higher A254 waters), greatly benefiting from DOC-normalized PAC dose increase. PAC/Alum/MF also attained 29–47% NOM median removal, decreasing THMFP by 26%. PAC complemented NOM removal by coagulation (+15–19%), though with no substantial improvement towards THMFP and membrane fouling. Furthermore, PAC/Alum/MF was a full barrier against aerobic endospores, and PAC dosing was crucial for ≥1.1-log reduction in bacteriophages.


Author(s):  
Guifang Li ◽  
Yuting Gao ◽  
Wuchang Song ◽  
Fei Xu ◽  
Yonglei Wang ◽  
...  

Abstract Increased pollution caused by socio-economic development has led to compound-contaminated high-hardness water pollution. In this study, laboratory-scale nanofiltration (NF) treatment of such water was investigated. Response-surface methodology was used to optimize the NF operating parameters, and a regression model with desalination rate and transmembrane pressure changes as response values was established. The NF membrane efficiencies in contaminant removal from groundwater and surface water with compound-contaminated high hardness and the membrane-fouling characteristics during long-term operation were investigated. The results show that the optimal operating parameters for the NF membrane in the removal of inorganic salts from groundwater are as follows: influent pH 8, influent pressure 1 MPa, and water yield 27.976%. The removal rates for groundwater total hardness, total alkalinity, total soluble solids, K+, Na+, Ca2+, Mg2+, , Cl−, , and were 99.4, 90.3, 84.7, 63.2, 56.8, 99.6, 95.2, 99.6, 68.3, 86.1, and 65.9%, respectively. Surface water contains more complex components; therefore, membrane fouling during surface water is more serious. The NF membrane was operated continuously for more than 35 days under the optimal operating conditions with no serious membrane fouling.


Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2606 ◽  
Author(s):  
Shujuan Meng ◽  
Minmin Zhang ◽  
Meng Yao ◽  
Zhuguo Qiu ◽  
Yubin Hong ◽  
...  

Membrane technologies have been widely applied in surface water treatment for drinking water purification. The main obstacles to the large scale application of membranes include membrane fouling, energy consumption and high investment. This study systematically investigated the performance of a hybrid system including in-situ coagulation and membrane module. The key parameters of a membrane system, including initial flux, operation mode (intermediate or continuous, time intervals, backwashing and aeration) was comprehensively investigated. In addition, the treatment performance in terms of turbidity, organic matter removal, membrane fouling and cleaning, and the effect of coagulants, were also studied. It was found that flat ceramic membranes with in-situ coagulation for surface water treatment performed much better without aeration and frequent backwashing, which gave interesting and important implications for future applications of a flat ceramic membrane, especially in drinking water purification. The hybrid system can achieve a high-water flux of 150 L/m2·h (LMH) for 8 h operation without aeration and backwash. The removal of turbidity, UV254 and COD can achieve 99%, 85% and 81%, respectively. The cake layer on the membrane surface formed from the coagulation flocs turned out to prevent the membrane to be exposed to organic pollutant immediately which minimized the fouling problem. In addition, the fouling layer on the membrane surface can be easily cleaned by air scouring and backwash at the end of experiments, with a water flux recovery of higher than 90%. These results in this study provided an alternative strategy for membrane fouling control and energy conservation.


2014 ◽  
Vol 48 ◽  
pp. 508-518 ◽  
Author(s):  
Fei Chen ◽  
Sigrid Peldszus ◽  
Ramila H. Peiris ◽  
Aki S. Ruhl ◽  
Renata Mehrez ◽  
...  

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 490
Author(s):  
Petros Gkotsis ◽  
Dimitra Banti ◽  
Anastasia Pritsa ◽  
Manassis Mitrakas ◽  
Petros Samaras ◽  
...  

This is the first study that examines the effect of operating conditions on fouling of Membrane Bio-Reactors (MBRs), which treat municipal wastewater in field conditions, with specific regard to the controlled development of filamentous microorganisms (or filaments). The novelty of the present work is extended to minimize the dissolved oxygen (DO) in recirculated activated sludge for improving the process of denitrification. For this purpose, two pilot-scale MBRs were constructed and operated in parallel: i) Filament-MBR, where an attempt was made to regulate the growth of filaments by adjustment of DO, the Food-to-Microorganisms (F/M) ratio and temperature, and ii) Control-MBR, where a gentle stirring tank was employed for the purpose of zeroing the DO in the recycled sludge. Results showed that low temperature (< 15 °C) slightly increased the number of filaments in the Filament-MBR which, in turn, decreased the Trans-Membrane Pressure (TMP). As the Soluble Microbial Products (SMP) and the colloids are considered to be the basic foulants of membranes in MBR systems, specific attention was directed to keep their concentration at low values in the mixed liquor. The low F/M ratio in the aeration tanks which preceded the membrane tank was achieved to keep the SMP proteins and carbohydrates at very low values in the mixed liquor, i.e., less than 6 mg/L. Moreover, as a result of the low recirculation rate (2.6∙Qin), good aggregation of the produced excess sludge was achieved, and low concentration of colloids with a size ≤50 nm (nearly the membranes’ pore size used for filtration/separation) was measured, accounted for maximum 15% of the total colloids. Additionally, the increase in filamentous population at the Filament-MBR contributed to the further reduction of colloids in the mixed liquor at 7.9%, contributing beneficially to the reduction of TMP and of membrane fouling. The diminishing of DO in the recirculated sludge improved denitrification, and resulted in lower concentrations of Ν-NO3− and TN in the effluent of the Control-MBR. Furthermore, the recirculation rate of Qr = 2.6∙Qin, in comparison with Qr = 4.3∙Qin, resulted in improved performance regarding the removal of N-NH4+. Finally, high organics removal and ammonium nitrification was observed in the effluent of both pilots, since COD and Ν-ΝΗ4+ concentrations were generally in the range of 10–25 mg/L and < 0.1 mg/L, respectively.


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